Process for preparing aromatic nitriles



United States Patent PROCESS FOR PREPARING AROMATIC NITRILES William G. Toland, Jr., San Rafael, Califl, assignor to California Research Corporation, San Francisco, Calif., a corporation of Delaware 7 No Drawing. Application January 4, 1954, Serial No. 402,143

4 Claims. (Cl. 260-465) This invention relates to a process for preparing organic cyanides. More particularly, the invention is concerned with a novel method for the production of useful cyano aromatic hydrocarbons.

Cyano-substituted aromatic hydrocarbons such as cyano-benzene are valuable intermediates in the manufacture of important chemicals. These compounds which are also known as cyanides and nitriles are conveniently reduced to the corresponding amines or hydrolyzed to the acids.

I have now found that cyanobenzenes can be prepared by a novel process which comprises heating benzene and copper cyanide to a temperature above about 175 C.

Other aromatic hydrocarbons than benzene may be converted to cyano-substituted aromatic hydrocarbons pursuant to the process of my invention. Such aromatic hydrocarbons may be any aromatic, alkyl aromatic or cycloalkyl aromatic hydrocarbon including the mononuclear and polynuclear types of fused and isolated rings. Examples of suitable aromatic hydrocarbons of these types, in addition to benzene, include diphenyl, terphenyl, naphthalene, anthracene, phenanthrene, indan, indene, indacene, toluene, xylene, ethyl benzene, cumene, tertiary butyl benzene, para-cymene, cyclohexyl benzene, dodecyl benzene, diphenyl methane and triphenyl methane. The aromatic hydrocarbons such as diphenyl, terphenyl, naphthalene, anthracene, phenanthrene and particularly benzene are preferred.

The copper cyanide may be cuprous cyanide, cupric cyanide, cupric cyanide plus cyanogen, etc. A copper cyanide is preferred.

The reaction is carried out at elevated temperatures above about 175 C. In the preferred operation, the temperature should not exceed the critical point of the aromatic hydrocarbon. Temperatures of 175-375 C. and particularly those from 260-360 C. are most satisfactory.

Solvents may also be employed in the reaction but are not considered essential. When high molecular weight 2,780,637 Patented Feb. 5, 1957 cyano-substituted aromatic hydrocarbons are prepared, it is convenient to use a low molecular weight paraflinic hydrocarbon solvent such as isopentane to facilitate handling of the materials.

As a further illustration of the invention, the following example is submitted. The proportions given are on a Weight basis unless otherwise specified.

Example Into a 4.5 liter stainless steel autoclave were charged 780 grams of benzene and 180 grams of cuprous cyanide. The autoclave was heated to 330 C. and maintained at this temperature for 2.5 hours with continuous shaking. The pressure in the autoclave rose autogenously to 825 p. s. i. g. The autoclave was cooled and the products of the reaction transferred to a still equipped with a distillation column. Benzene was recovered by distillation. Following the distillation of the benzene, benzonitrile was recovered having a boiling point of l-l93 C. and the distinctive odor of benzonitrile.

Following the distillation of benzonitrile, a heavier higher boiling fraction was separated. This fraction contained polycyanobenzenes.

The process can also be carried out continuously, as Well as batchwise, as illustrated by the above example. In the preferred practice of the invention, the process is operated to give low conversions per pass and the unconverted aromatic hydrocarbon recycled. Over-oxidation of the product is thus avoided and higher yields are obtained.

I claim:

1. A process for preparing aromatic nitriles which comprises heating an aromatic hydrocarbon and a copper cyanide to a temperature in the range from 375 C., the copper cyanide being the sole source of the cyano radical, and recovering the aromatic nitrile.

2. A process for preparing benzonitrile which comprises heating benzene and a copper cyanide to a temperature above about 175 C. said copper cyanide being the sole source of the cyano radical.

3. A process for preparing benzonitrile which comprises heating benzene and a copper cyanide to a temperature in the range from 175375 C. said copper cyanide being the sole source of the cyano radical.

4. A process for preparing benzonitrile which comprises heating benzene and a copper cyanide to a temperature in the range from 260-360 C. said copper cyanide being the sole source of the cyano radical.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A PROCESS FOR PREPARING AROMATIC NITRILES WHICH COMPRISES HEATING AN AROMATIC HYDROCARBON AND A COPPER CYAMIDE TO A TEMPERATURE IN THE RANGE OF FROM 175-375*C., THE COPPER CYANIDE BEING THE SOLE SOURCE OF THE CYANO RADICAL, AND RECOVERING THE AROMATIC NITRILE. 